CHAPEL HILL -- When fish is not contaminated, moderate consumption of the
protein-rich food source by pregnant women and young children appears to boost
the children’s neurological development, a new study shows.

"Our research adds to the literature suggesting that fish contains
nutrients that may enhance early brain development," said Dr. Julie
Daniels, assistant professor of epidemiology at the University of North Carolina
at Chapel Hill School of Public Health. "We can not say that we have proven
that eating fish will have long-lasting effects in making people smarter since
we have only looked at early development markers through an observational
study."

More research is needed to corroborate the findings, Daniels said.

A report on the study appears in the July issue of the journal Epidemiology.
Besides Daniels, authors are Drs. Matthew P. Longnecker of the National
Institute of Environmental Health Sciences, Andrew S. Rowland of the University
of New Mexico’s family and community medicine department and Jean Golding of
the University of Bristol Institute of Child Health’s ALSPAC Study Team.

Conducted in Bristol, England, the research involved evaluating the
association between mothers’ fish intake during pregnancy and their offspring’s
early development of language and communication skills, Daniels said.

The team evaluated 7,421 English children born in 1991 and 1992. They studied
the children since much has been learned about contaminants in fish, but little
research has been done on the potential developmental benefits of eating fish,
she said.

"We measured mothers’ and children’s fish intake by
questionnaire," Daniels said. "Later, we assessed each child’s
cognitive development using adaptations of the MacArthur Communicative
Development Inventory at 15 months and the Denver Developmental Screening Test
at 18 months."

Researchers also measured mercury levels in umbilical cord tissue for a
subset of 1,054 children.

"We found total mercury concentrations to be low and not associated with
neurodevelopment," she said. "Fish intake by mothers during pregnancy,
and by infants after birth, was associated with higher mean developmental
scores. For example, the adjusted mean MacArthur comprehension score for
children whose mothers consumed fish four or more times a week was 72 compared
with 68 among those whose mothers did not consume fish. While this may not be a
major difference clinically, but the statistically significant results were
consistent across related subtests that could be important across a large
population."

Scientists found that there was a subtle but consistent link between eating
fish during pregnancy and children’s subsequent test scores, even after
adjusting for factors such as the age and education of the mother, whether she
breastfed and the quality of the home environment.

The largest effect was seen in a test of the children’s understanding of
words at age 15 months. Children whose mothers ate fish at least once a week
scored 7 percent higher than those whose mothers never ate fish.

A similar pattern, although less marked, was seen in tests measuring social
activity and language development. Developmental scores were also higher among
children who also ate fish at least once a week before their first birthdays.

The study suggests that if a woman eats moderate quantities of fish -- about
two to three servings per week, or 12 ounces, of non-contaminated species -- her
child might benefit, the scientist said. There is no evidence that the more fish
a woman eats, the higher that benefit would be.

"Women should definitely avoid shark, swordfish, king mackerel and
tilefish, according to the U.S. Environmental Protection Agency and Food and
Drug Administration," Daniels said. "Those fish are higher on the food
chain and have greater accumulation of pollutants."

Depending on the region where they are caught, many of the most commonly
eaten fish are low in pollutants while still being high in critical long-chain
fatty acids and other nutrients, she said. They include salmon, herring, pollock,
canned light tuna and sardines.

Daniels said she is pursuing similar work in a group of U.S. children to
confirm the results in other populations.

"We also need to follow the children longer to determine whether any
benefits from fish intake are permanent or transient," she said.

Fish intake during pregnancy has the potential to improve fetal development
because it is a good source of iron and long chain omega fatty acids, which are
necessary for proper development and function of the nervous system, Daniels
said. Fish, especially oily fish, is a dietary source of eicosapentaenoic and
docosahexaenoic acids (DHA), which are important in the structural and
functional development of the brain before birth and through a child’s first
year. The concentration of DHA in fetal brain increases rapidly during the last
three months in the womb.

The Avon Longitudinal Study of Parents and Children, or ALSPAC, (also known
as Children of the 90s) is a continuing research project based at the University
of Bristol. It enrolled 14,000 mothers during pregnancy in 1991-2 and has
followed the children and parents in minute detail ever since

Support for the study came from the Medical Research Council, the Wellcome
Trust, the Department of Health, the Department of the Environment, DfEE,
Nutricia and other companies, all in the United Kingdom.